It is known to use hydrophilic polymer coatings to reduce moisture fogging. The most effective of these coatings use soluble polymers which have a short life since they wash off. Polymers which are less hydrophilic, though more permanent, have more limited anti-fogging properties. It is also known to use pure surfactant solutions which function by depositing a soap film causing water droplets to spread. Such films also have a short life since they wash off. The same is true of hydrophilic polymer anti-fog coatings to which silicone based surfactants have been added since the surfactant still exists in a soluble form (see Canadian Pat. No. 1,012,283). U.S. Pat. No. 4,119,094, incorporated herein by reference, discloses slippery coatings of polyvinylpyrrolidone-polyurethane interpolymers which do not have good anti-fog properties.
The problems of the prior art have been solved by complexing or reacting surfactants with hydrophilic polymers that have been crosslinked with isocyanate prepolymers to provide hard, insoluble coatings with improved fog resistance, adhesion, scratch resistance and life. As used herein and in the claims, the term polymer is intended to include copolymers.